The present invention relates to a method of, and the apparatus for, testing the rigidity and strength of the components of a torsional drive system. More specifically the invention provides for the balanced or symmetrical capturing of the torque produced by the drive system within the drive system itself, while allowing access to the torsional output shaft and its associated coupling, keyways and key.
Torsional drive systems are used to operate a wide variety of equipment and machinery. Where torsional drive systems are required to produce large output torques, such as for the operation of drawbridges and lock gates, the continued operational reliability of the drive system is extremely important. Therefore torsional drive systems are often required to be tested prior to installation at, or above, full operational torsional loads. Such tests help to ensure that the torsional drive system is capable of producing the required torsional output without malfunctioning.
Previously, tests were conducted utilizing means such as large concrete sliding blocks to create the load torque to resist the drive system. The testing of torsional drive systems has therefore been quite expensive and very difficult to balance for pure torsion. It has therefore been found desirable to provide a method and apparatus for testing drive systems which allow the drive system to be tested at a nominal cost and with readily assureable balanced loads that do not generate harmful bending or radial forces not capable of being handled by the drive machinery.
Torsional drive systems generally include a motor, one or more reducers, and various couplings for producing a torque at an output shaft. A flexible gear coupling is usually used to transmit the torque from the output shaft to whatever is desired to be driven. The output shaft and coupling are connected with a key which fits within a keyway in the shaft and in the coupling. The fit of the key within the keyways has been found to be critical to the long operational life of the drive system. Where the key fits too loosely within the keyways, the output shaft and coupling will be subject to increased stress during operation which leads to metal fatigue, stress induced cracks, and progressive loosening.
While the fit of the key within the keyways may be measured with feeler gauges and other means prior to installation of the drive system, to obtain a realistic indication of the key's fit, measurements must be taken before, after and while the output shaft and coupling are being subjected to full operating torsional loads. It has therefore also been found desirable to conduct the above-mentioned test of the drive system in such a manner that access may be had to the key and keyways while the drive system is producing a full operating or test torsional load and to attach monitoring devices such as strain gauges or ultrasound transducers to warn of changes within the drive system.